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        <div>
            <div><h3 class="title">
                <a name="asio.reference.asio_handler_invoke"></a><a class="link" href="asio_handler_invoke.html"
                                                                    title="asio_handler_invoke">asio_handler_invoke</a>
            </h3></div>
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    <p>
        <a class="indexterm" name="asio.indexterm.asio_handler_invoke"></a>
    </p>
    <p>
        (Deprecated: Use the <a class="link" href="associated_executor.html" title="associated_executor"><code
            class="computeroutput"><span class="identifier">associated_executor</span></code></a> trait.) Default
        invoke function for handlers.
    </p>
    <p>
        Default handler invocation hook used for non-const function objects.
    </p>
    <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <span class="identifier">Function</span><span class="special">&gt;</span>
<span class="identifier">asio_handler_invoke_is_deprecated</span> <a class="link"
                                                                     href="asio_handler_invoke/overload1.html"
                                                                     title="asio_handler_invoke (1 of 2 overloads)">asio_handler_invoke</a><span
                class="special">(</span>
    <span class="identifier">Function</span> <span class="special">&amp;</span> <span class="identifier">function</span><span
                class="special">,</span>
    <span class="special">...</span> <span class="special">);</span>
  <span class="emphasis"><em>» <a class="link" href="asio_handler_invoke/overload1.html"
                                  title="asio_handler_invoke (1 of 2 overloads)">more...</a></em></span>
</pre>
    <p>
        Default handler invocation hook used for const function objects.
    </p>
    <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <span class="identifier">Function</span><span class="special">&gt;</span>
<span class="identifier">asio_handler_invoke_is_deprecated</span> <a class="link"
                                                                     href="asio_handler_invoke/overload2.html"
                                                                     title="asio_handler_invoke (2 of 2 overloads)">asio_handler_invoke</a><span
                class="special">(</span>
    <span class="keyword">const</span> <span class="identifier">Function</span> <span class="special">&amp;</span> <span
                class="identifier">function</span><span class="special">,</span>
    <span class="special">...</span> <span class="special">);</span>
  <span class="emphasis"><em>» <a class="link" href="asio_handler_invoke/overload2.html"
                                  title="asio_handler_invoke (2 of 2 overloads)">more...</a></em></span>
</pre>
    <p>
        Completion handlers for asynchronous operations are invoked by the <a class="link" href="io_context.html"
                                                                              title="io_context"><code
            class="computeroutput"><span class="identifier">io_context</span></code></a>
        associated with the corresponding object (e.g. a socket or deadline_timer).
        Certain guarantees are made on when the handler may be invoked, in particular
        that a handler can only be invoked from a thread that is currently calling
        <code class="computeroutput"><span class="identifier">run</span><span class="special">()</span></code>
        on the corresponding <a class="link" href="io_context.html" title="io_context"><code
            class="computeroutput"><span class="identifier">io_context</span></code></a> object. Handlers may
        subsequently be invoked through other objects (such as <a class="link" href="io_context__strand.html"
                                                                  title="io_context::strand"><code
            class="computeroutput"><span class="identifier">io_context</span><span class="special">::</span><span
            class="identifier">strand</span></code></a> objects) that provide additional
        guarantees.
    </p>
    <p>
        When asynchronous operations are composed from other asynchronous operations,
        all intermediate handlers should be invoked using the same method as the
        final handler. This is required to ensure that user-defined objects are not
        accessed in a way that may violate the guarantees. This hooking function
        ensures that the invoked method used for the final handler is accessible
        at each intermediate step.
    </p>
    <p>
        Implement asio_handler_invoke for your own handlers to specify a custom invocation
        strategy.
    </p>
    <p>
        This default implementation invokes the function object like so:
    </p>
    <pre class="programlisting"><span class="identifier">function</span><span class="special">();</span>
</pre>
    <p>
        If necessary, the default implementation makes a copy of the function object
        so that the non-const operator() can be used.
    </p>
    <h5>
        <a name="asio.reference.asio_handler_invoke.h0"></a>
        <span><a name="asio.reference.asio_handler_invoke.example"></a></span><a class="link"
                                                                                 href="asio_handler_invoke.html#asio.reference.asio_handler_invoke.example">Example</a>
    </h5>
    <pre class="programlisting"><span class="keyword">class</span> <span class="identifier">my_handler</span><span
            class="special">;</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span
                class="identifier">Function</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">asio_handler_invoke</span><span class="special">(</span><span
                class="identifier">Function</span> <span class="identifier">function</span><span
                class="special">,</span> <span class="identifier">my_handler</span><span class="special">*</span> <span
                class="identifier">context</span><span class="special">)</span>
<span class="special">{</span>
  <span class="identifier">context</span><span class="special">-&gt;</span><span class="identifier">strand_</span><span
                class="special">.</span><span class="identifier">dispatch</span><span class="special">(</span><span
                class="identifier">function</span><span class="special">);</span>
<span class="special">}</span>
</pre>
    <h5>
        <a name="asio.reference.asio_handler_invoke.h1"></a>
        <span><a name="asio.reference.asio_handler_invoke.requirements"></a></span><a class="link"
                                                                                      href="asio_handler_invoke.html#asio.reference.asio_handler_invoke.requirements">Requirements</a>
    </h5>
    <p>
        <span class="emphasis"><em>Header: </em></span><code class="literal">asio/handler_invoke_hook.hpp</code>
    </p>
    <p>
        <span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
    </p>
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            <div class="copyright-footer">Copyright © 2003-2022 Christopher M. Kohlhoff<p>
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                file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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